In the development of military munitions devices it is often desirable to retrieve a test projectile or spent munitions device from its location of finally coming to rest (whether above ground or buried). Such removal serves the purposes of projectile (or warhead) study and improvement and also serves a test range cleanup function of removing the hazard such devices present to persons and equipment and future testing conducted in the same area of a testing range if not removed. In the testing of military hardened target-compatible munitions it is often desirable for example to study the integrity of the penetrator portion of a projectile or study the experimental content of a projectile for target impact-incurred damage and for penetrator integrity-improvement purposes. Such information is desirable in the case of both air launched munitions devices such as bombs and cannon shells and for artillery launched munitions including howitzer projectiles and naval munitions. The thus-acquired information supports development of new materials and structures.
FIG. 4 in the drawings herein shows a test of this type involving a typical reinforced concrete target 401. The FIG. 4 target 401 has been penetrated by a 4-inch diameter projectile in an event producing target concrete spalling and exposure of reinforcing bars. The usual recovery method for a projectile involved in the FIG. 4 scene is to visually sift through front-end loader bucket volumes of soil from the backstop mound 410 as the soil is slowly dumped from an elevated position. Since the projectile trajectory in the backstop soil is unstable and random, projectile turns are common, and one must frequently examine numerous front-end loader bucket volumes and empty the loader slowly, often searching for hours before locating the projectile. Furthermore, such visual searching may fail if the projectile is hidden by a concurrently falling quantity of soil or by other real world effects.
In FIG. 4 however there is represented an actual photo of a buried projectile recovery that was accomplished in accordance with the present invention. The location accomplished in this present invention manner is sufficiently accurate to enable projectile recovery in minutes of time and by the FIG. 4 illustrated manual shoveling. As described below herein such present invention projectile location is accomplished through use of a UHF signal radiating through the ground from the usually buried test projectile. In addition to the FIG. 4 focused-area recovery, projectiles to be located may also penetrate both the target 401 and the backstop earth 410 and may also glance off the backstop earth to (with the present invention) result in an open field projectile and beacon hunt, usually involving many personnel searching through tall grass (in the case of a Florida or other open test range). A surviving beaconaccording to the present invention, whether buried or not, cuts the time and personnel required for recovery of the projectile regardless of its resting point and whether the projectile is carrying an experiment or other recoverable cargo. Larger munitions launched from aircraft for example are subject to these same difficulties and may use the system described herein for similar recovery efforts. Electronics including an amplifier appropriate to the increased range of these larger devices, and a larger antenna scaled to fit may be desired in these instances.
Although these discussions are premised on the usual case of recovering test or dud munitions devices the same difficulties exist with obvious compounding in the exceptional cases of needing to locate and remove a live munitions test device that has failed to detonate. Although such instances are rare and avoided through use of great care, Murphy""s Law, the rules of statistical sampling and similar real world algorithms assure their occasional occurrence. In such exceptional instances the need for precise spent projectile location is, if anything, even greater and additional complexities such as time delay considerations and the need to use protective measures during the search are present.
Electronic locator devices intended to fill these needs may be understood to involve several special requirements not of concern in most electronic circuit uses. Perhaps the most difficult of these requirements is a tolerance for the deceleration forces experienced by a projectile or other penetrator device such as for example a bomb. Additional considerations include a locator device operating life measuring in at least tens of hours and preferably in a plural number of daysxe2x80x94until retrieval is safe and convenient. In addition small physical size and mass, moisture immunity and temperature immunity over at least moderate ranges are also significant needs. Often as in the case of the below-disclosed preferred embodiment of the invention these requirements become substantially intertwined so that for example an increase in operating life is possible at the expense of unacceptable increased battery size and mass and impact deceleration vulnerability. In the latter instance for example a larger locator beacon battery is more susceptible to deceleration damage and can be damaged by its own inertia in spite of a surviving protective encasement. This relationship alone is a significant factor in seeking to minimize beacon mass and energy requirements and is the prompter for one special aspect of the present invention.
Locator devices need not however be of the operating power level, detailed information providing and continuous performance nature required in the above two identified and incorporated by reference herein munitions penetration sequence data retrieval devices and their patent documents. The present beacon can instead be of a lower power, simplified signal form and of a more economical arrangement as is disclosed herein. With respect to impact tolerance the beacon of the present invention must of course survive the deceleration forces incurred when the host warhead strikes the earth or other object however it need not function during the interval of warhead deceleration. An additional notable difference between the present invention and those of the above identified and incorporated by reference copending patent documents involves the desire for smaller antenna sizes for projectile use and the resulting selection of a higher operating frequency for the present invention and of course the needed longer duration of an operating period (in contrast with an operating period measured only in milliseconds in the copending documents invention) once operation is commenced in the case of the present beacon invention.
The present invention provides an impact resistant low cost radio frequency beacon apparatus usable over a relatively long operating life, for locating and recovering a deployed munitions device at a test range or other site. The invention is of course not limited to test range use and may be employed in numerous other need-to-locate applications in both military and non-military environments.
It is an object of the present invention therefore to provide a munitions locator beacon.
It is another object of the invention to provide a munitions locator beacon capable of operating in the environment experienced by a munitions warhead device.
It is another object of the invention to provide a munitions locator beacon capable of operating without spatial interference to the contents of its host projectile.
It is another object of the invention to provide a munitions locator beacon capable of operating within the impact deceleration, size, weight, burial and operating life constraints of a munitions projectile in a test range environment.
It is another object of the invention to provide a launching and impact deceleration-protection arrangement for the small electronics package of a munitions locator beacon apparatus.
It is another object of the invention to provide an energy conserving modulation arrangement for the output signal of a munitions device locator beacon.
It is another object of the invention to provide a munitions device locator beacon having a multiple aspect (including multiple frequency component) impact shock protection arrangement.
It is another object of the invention to provide a munitions device locator beacon which can predictably withstand the extreme impact shock forces encountered in penetrating two foot reinforced concrete targets at 1234 feet per second when attached to the tail of a 54 pound munitions projectile.
It is another object of the invention to provide a munitions device locator beacon capable of transmitting through clay-sand over distances of up to 36 feet in order to promotes rapid location and efficient recovery of spent munitions projectiles.
These and other objects of the invention will become apparent as the description of the representative embodiments proceeds.
These and other objects of the invention are provided by spent test-munitions projectile retrieval, high G force resistant low energy requirement locator beacon apparatus comprising the combination of:
a selectively configured elastic resin material housing disposable in a rear location of said test-munitions projectile prior to projectile airborne launch;
an integrated circuit chip assembly received in said selectively configured material housing and having a radio frequency energy generating integrated circuit module with an insulating material layer and an overlying selectively energy absorbing and reflecting metallic layer covering attached elastic resin one face thereof;
said integrated circuit assembly further including a radio frequency energy generating chip and a keying modulator circuit of selected distinctive audio frequency keying pattern and less than twenty-five percent radio frequency energy generating integrated circuit chip output duty cycle characteristics;
a source of electrical energy of said duty cycle and selected audio frequency keying pattern-enabling limited size and mass connected with said keying modulator circuit and said radio frequency energy generating chip;
a tubular enclosure member surrounding said integrated circuit assembly and disposed within said elastic resin material housing along one axis thereof;
a radio frequency antenna member disposed within an axial extremity portion of said organic material housing and connected with a radio frequency energy output port of said integrated circuit assembly;
a portable radio frequency energy receiver, hand cartable to a selected search vicinity location for said spent test-munitions projectile.